This question already has an answer here:
I intend to travel to the US for a month, and I would really like to use a lot of data traffic during the trip, for browsing, maps, Skype calls, etc. How can I do that? Should I buy a SIM? Do I have to order one in advance, or are data SIMs readily available in the airport? Is there any website that can show me competing options and maybe compare them?
Also, I guess SIMs are linked to one specific carrier. Does it matter which cellular carrier I choose, or do all have similar coverage and do all support GSM phones? Does it change from state to state? e.g. do some of the more states, like Hawaii, have limited coverage for some of the carriers?
In short I am clueless here, and would really appreciate any information about this.
EDIT: meanwhile I have found this comparison between various data sim suppliers, seems very useful though I'm not sure how reliable or up-to-date this page is.